1. Field of the Invention
The present invention relates generally to a method and apparatus for modeling the effects of cosmic rays on microelectronics in earth orbit, and more particularly to an improved method and apparatus for modeling these effects, these improvements reflecting a simpler, easier way for the user to operate the model over the internet, and more accurate modeling of these effects.
2. Description of the Related Art
For electronic components onboard satellites in earth orbit, exposure to cosmic rays represents a serious risk, due to the capacity of cosmic rays to induce single event effects (SEE) in these components. See generally Sherra E. Kerns, Transient-Ionization and Single-Event Phenomena, in Ionizing Radiation Effects in MOS Devices and Circuits 485-91 (John Wiley & Sons, Inc., T. P. Ma et al. eds., 1989). In brief, SEEs occur when an energetic particle changes a particular device in an integrated circuit, thereby causing an error. To date, the only effective methods for hardening these circuits against SEEs have been shielding, redundancy, and error detection and correction (EDAC).
Unfortunately, these measures are not always effective, and the failure of a single component may lead to the total loss of a multi-million dollar satellite. With the potential loss associated with this risk so high it is desired to have a way to accurately predict the magnitude of this risk, as well as a way of predicting how successful ameliorative efforts are likely to be.
CREME (short for Cosmic Ray Effects on Microelectronics) was a software package developed by the Naval Research Laboratory in 1981 for modeling how a given electronic chip on a given satellite with a given orbit and amount of shielding would hold up against cosmic ray bombardment. See Cosmic Ray Effects on Microelectronics, Part I: The Near-Earth Particle Environment, Adams et al., NRL Memorandum Report 4506; Cosmic Ray Effects on Microelectronics Part II: The Geomagnetic Cutoff Effects, Adams et al., NRL Memorandum Report 5099; Cosmic Ray Effects on Miroelectronics, Part IV, Adams, NRL Memorandum Report 5901, each incorporated herein by reference, in their entireties, for all purposes. CREME had several shortcomings. It has been discovered that many of the predictions of CREME were inaccurate. Particular shortcomings of the original CREME software included its inaccurate modeling of the transmission of cosmic rays through earth's magnetosphere, and inaccurate modeling of the flux of heavy ions associated with solar flares.
Moreover, the implementation of this program was less than optimal, having a difficult user interface, and requiring each user to install, maintain, and run the software.